CString, QString, char*之间的转换(包括VC编译开关)

时间:2021-02-14 19:14:19

传给未分配内存的const char* (LPCTSTR)指针.
CString cstr(asdd);
const char* ch = (LPCTSTR)cstr;
ch指向的地址和cstr相同。但由于使用const保证ch不会修改,所以安全.2.传给未分配内存的指针.
CString cstr = "ASDDSD";
char *ch = cstr.GetBuffer(cstr1.GetLength() + 1);
cstr.ReleaseBuffer();
//修改ch指向的值等于修改cstr里面的值.
//PS:用完ch后,不用delete ch,因为这样会破坏cstr内部空间,容易造成程序崩溃.
3.第二种用法。把CString 值赋给已分配内存的char *。
CString cstr1 = "ASDDSD";
int strLength = cstr1.GetLength() + 1;
char *pValue = new char[strLength];
strncpy(pValue, cstr1, strLength);
4.第三种用法.把CString 值赋给已分配内存char[]数组.
CString cstr2 = "ASDDSD";
int strLength1 = cstr1.GetLength() + 1;
char chArray[100];
memset(chArray,0, sizeof(bool) * 100); //将数组的垃圾内容清空.
strncpy(chArray, cstr1, strLength1);

如果上述都不行:
CString转换为char*
CString origCString("Hello, World!");
wchar_t* wCharString = origCString.GetBuffer(origCString.GetLength()+1);
size_t origsize = wcslen(wCharString) + 1;
size_t convertedChars = 0;
char *CharString;
CharString=new char(origsize);
wcstombs_s(&convertedChars, CharString, origsize, wCharString , _TRUNCATE);
cout << CharString << endl;
成功输出字符串"Hello,World"

原因:
原来在VC++ 2005以前,应用程序默认都是关闭对Unicode的支持的,而在VC2005中,默认打开了对它的支持,CString对应的字符串应该是TCHAR,TCHAR的定义是这样的,
#ifdef _UNICODE
typedef wchar_t TCHAR ;
#else
typedef char TCHAR;
#endif
所以在工程中应该可以关闭对于Unicode的支持,从而可以直接转换。这个做法是右击工程名—〉Property—〉General中的character set中选择notset,这样,本文开头的那段代码就可以正确的执行了。

如何将QString转换为char *或者相反

How can I convert a QString to char* and vice versa ?(trolltech)

Answer:
In order to convert a QString to a char*, then you first need to get a latin1 representation of the string by calling toLatin1() on it which will return a QByteArray. Then call data() on the QByteArray to get a pointer to the data stored in the byte array. See the documentation:

See the following example for a demonstration:

int main(int argc, char **argv)
{
QApplication app(argc, argv);
QString str1 = "Test";
QByteArray ba = str1.toLatin1();
const char *c_str2 = ba.data();
printf("str2: %s", c_str2);
return app.exec();
}
Note that it is necessary to store the bytearray before you call data() on it, a call like the following
const char *c_str2 = str2.toLatin1().data();

will make the application crash as the QByteArray has not been stored and hence no longer exists.

To convert a char* to a QString you can use the QString constructor that takes a QLatin1String, e.g:

QString string = QString(QLatin1String(c_str2)) ;

还有其他多种方法:

方法一 -----------------------------------------
#define G2U(s) ( QTextCodec::codecForName("GBK")->toUnicode(s) )
#define U2G(s) ( QTextCodec::codecForName("GBK")->fromUnicode(s) )

QString str;
QCString cstr;

str = G2U("中文输入");
cstr = U2G(str);

QCString有这样一个重载运算符
operator const char * () const

可以这样
printf("%s\n", (const char*) cstr);
或是copy出来
char buf[1024];
strcpy(buf, (const char*) cstr);

方法二 -----------------------------------------
如果是中文系统

直接用 (const char*) str.local8Bit()
例如
printf("%s", (const char*) str.local8Bit());

str是一个QString

方法三 -----------------------------------------
char str[64];
QTextCodec *textcod = QTextCodec::codecForName("GBK");
QCString string1 = textcod ->fromUnicode(listbox1->currentText());
strcpy(str,string1);

QString和Std::string

从char*到 QString可以从fromLocal8Bit()转化
std::string有c_str()的函数使再转化为char*

QString有toAscii()记不清了你可以看看.又是我的粗心酿成大错,我重新查看了一下Qt文档,原来Qt可以直接从std::wstrin*生一个QString,用QString::fromStdWString(const std::wstring &)这个静态成员函数即可。我试了试用std::string的c_str()返回的char *构造的QString不能再保存原先的中文信息,而用std::wstring构造的QString则可以用qDebug()输出原先的中文信息

GB编码与UTF8编码的转换
在主函数app后加上这句:

QTextCodec::setCodecForLocale(QTextCodec::codecForName("GB18030"));

然后是从UTF8编码到GB编码的字符串转换方法:

QString Utf8_To_GB(QString strText)
{
return QString::fromUtf8(strText.toLocal8Bit().data());
}

至于从GB到UTF8,那大家就经常用了:

QString GB_To_Utf8(char *strText)
{
return QString::fromLocal8Bit(strText);
}

参考:http://www.cppblog.com/Alina-zl/archive/2008/11/19/67323.html